Aero Development Speer S-2-C
Produced in the 1920s, the Speer S-2-C features a solid master rod operating on roller bearings, and two piece crankshaft. The cast aluminium cylinder head are bolted to nickel iron brrel. The cylinder is of superposed or “F” head construction, the exhaust valve being in the head and the intake valve in the ell. The valves are operated by a special action that eliminates all parts outside the crankcase that require lubrication. The combustion chamber is of a type that provides high turbulence and resulting fuel economies.
All accessories are grouped at the rear of the engine for protection from the weather and to provide ease of maintenance.
Due to the fact that there are no babbit bearings, the need for high pressre lubrication has been eliminated, consequently only sufficient pressure is carried to serve as an indicationbthat oil is flowing.
Available at extra cost were Eclipse starter, Viking fuel pump, tools, and instruction book.
Type: 7 cyl air cooled radial
Power: 120 hp at 1800 rpm
Displacement: 491 cu.in
Bore: 4 1/8 in
Stroke: 5 1/4 in
Length: 27 3/8 in
Diameter: 38 1/2 in
Weight: 330 lb
Fuel consumption: not more than .53 lb/hp/hr
Oil consumption: not more than .025 lb/hp/hr
Lubrication: Pressure and scavenging gear pumps
Ignition: Dual Scintilla MN-7D
Carburation: Stromberg NAS5B
Spark Plugs: 2 Champion/cylinder